Double-plate gate valve and shut-off plate for use in a double-plate gate valve

ABSTRACT

A double-plate gate valve 10 is proposed which is provided for fittings of industrial plants, in particular chemical and petrochemical plants, wherein the double-plate gate valve 10 comprises a housing 11 having two shut-off plates 20a, 20b inside the housing 11 which are displaceable between an open and a closed position, wherein spring elements 25 such as disc spring packs are arranged between the shut-off plates 20a, 20b pressing the shut-off plates 20a, 20b in the closed position against sealing surfaces arranged on the housing 11 such that the entire sealing force required for sealing is provided by the spring elements 25. Furthermore are proposed a shut-off plate 20 for use in an inventive double-plate gate valve 10 as well as a method for sealing the inventive double-plate gate valve using the inventive shut-off plates.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional patent application of U.S.Nonprovisional patent application Ser. No. 15/072,972, filed Mar. 17,2016 which application claims priority to and the benefit of GermanPatent Application No. 10 2015 104 555.9, filed Mar. 26, 2015, thecontents of both of which as are hereby incorporated by reference hereinin their entirety.

BACKGROUND Technical Field

The invention relates to a double-plate gate valve for fittings ofindustrial plants, in particular chemical and petrochemical plants, acircular shut-off plate for use in a double-plate gate valve as well asa method for sealing a double-plate gate valve in closed position.

Description of Related Art

Plate gate valves are employed in the chemical and petrochemicalindustry, in particular in so-called coking plants and serve the purposeof obturating the coking drum in which the coking takes place. Due tothe high process temperatures and pressures, the employed valves need tobe sealed accordingly.

BRIEF SUMMARY

The present invention is therefore based on the task of creating adouble-plate gate valve featuring high tightness and simpleconstruction. It is moreover a task of the present invention to providea shut-off plate and a method for sealing a double-plate gate valve.

This task is solved by a double-plate gate valve as well as shut-offplates according to the pending claims, and a method for sealing adouble-plate gate valve according to the pending claims.

The task is in particular solved by a double-plate gate valve forfittings of industrial plants, in particular chemical and petrochemicalplants, comprising a housing having two shut-off plates inside thehousing which are displaceable between an open and a closed position,wherein spring elements such as disc spring packs are arranged betweenthe shut-off plates, pressing the shut-off plates in the closed positionagainst sealing surfaces arranged on the housing such that the entiresealing force required for sealing is provided by the spring elements.

An advantageous detail of the invention is in this case that the sealingforce required for sealing is entirely applied by the spring elementsclamped between the shut-off plates. Apart from the spring elements, thespace between the shut-off plates may be free from built-in components.Thereby, the double-plate gate valve's construction is simplified andhigh tightness achieved.

In at least one embodiment, the housing comprises at least one sealinggas connection through which a sealing gas pressure may be applied tothe inside of the housing. This results in an increase of theoperational safety when the double-plate gate valve is in the closedposition. In the case of failure of one or more spring elements and thusan associated deterioration of the sealing force, the sealing gaspressure is designed to compensate for the sealing force missing due tothe failed elements.

In yet another embodiment, the housing comprises an upper housingsealing seat and a lower housing sealing seat. These comprise sealingsurfaces against which the shut-off plates are pressed. In at least thisembodiment, the upper housing sealing seat is connected to the housingto be detachable so as to enable access to the shut-off plates. Thisrepresents a particularly simple maintenance option since the housing isthus not required to be opened, and the maintenance opening created inthis way is sufficiently large to remove at least the upper shut-offplate, in particular both shut-off plates without opening the housing.

In a further embodiment, the upper housing sealing seat comprises amultiple seal which forms part of the sealing surface against which theupper shut-off plate is pressed in the closed position. The tightness ofthe housing's inside is thereby additionally improved, in particularwith respect to gases generated during the coking.

It is further advantageous for the upper housing sealing seat to featurea sealing and scraping edge on its radial inner side which, in theclosed position, rests against the upper shut-off plate and thus forms ametal seal. When the upper shut-off plate is displaced, for example inthe transition from the closed to the opened position, contaminationscan thus be scraped off the upper shut-off plate. In addition, the uppershut-off plate's tightness in the closed position can be improved.

In yet another exemplary embodiment, the shut-off plates are inserted tobe movable in a spectacle-shaped plate box displaceable inside thehousing. This decoupling of displacing and sealing element offersnumerous advantages. On the one hand, the shut-off plates in theintended industrial plants are exposed to extreme thermal loads. Thanksto the decoupling of plate box and shut-off plate, the thermaldistortion of the plate box is minimized, and thus the guide within thehousing is not impaired. Furthermore, different materials for the platebox and the shut-off plate may in this way be selected so as to accountfor the special requirements in the respective industrial plant. Looselyinserting the shut-off plates finally facilitates their maintenance andreplacement.

Advantageously, a gap is formed between the shut-off plates, itssmallest width being less than the thickness of one of the shut-offplates at its outer circumference. This increases the double-plate gatevalve's operational safety since in the event of the sealing forcedeteriorating, for example due to individual spring elements failing,the plates will not deflect excessively.

Advantageously, to an outer edge of the plate box, a distal end of anactuating rod is further mounted which extends within the housing alongthe shut-off plate's displacement direction away from the plate box andby means of which the plate box and the shut-off plates mounted thereinare displaceable. This reduces the assembly and maintenance effort ofthe double-plate gate valve.

In the context of the invention, a circular shut-off plate for use in adouble-plate gate valve is further proposed. The inventive shut-offplate exhibits the following features: a flat outer side; a stop area,that is concentric to the plate circumference, on the inner side, thesurface of which runs in parallel to the outer side; a plate thicknessradially decreasing from the stop area toward the outside; and springelement seats for receiving spring elements regularly arranged along theplate circumference in the edge area on the inner side of the shut-offplate.

The inventive shaping of the shut-off plates results in furtheradvantages.

The stop area provided in the center of the shut-off plates functions asa safety element, since in the event of too high a load from outside theplates will contact in the stop area and further pushing be prevented.

Furthermore, due to the shut-off plate's reduced thickness toward theedge, less material is needed, whereby costs are saved.

Finally, the radial tapering of the shut-off plates promotes a convexcurvature of the shut-off plates upon pressure application in the closedposition, which results in improved sealing with respect to the sealingseats.

Lastly, a method for sealing a double-plate gate valve is proposedwithin the context of the invention, in that the shut-off plates arespread apart by spring elements such as spring disc packs clamped inbetween them and are pressed against respective associated sealingsurfaces on the double-plate gate valve's housing, wherein a sealing gaspressure is applied to the space between the shut-off plates forincreasing the sealing force.

Thus, in the inventive sealing method of the double-plate gate valve inthe closed position, the sealing force applied by the spring elements isfurther increased by applying pressure to the housing interior by meansof a sealing gas, which constitutes an additional safety measure duringoperation.

BRIEF DESCRIPTION OF THE FIGURES

Herein-below, the invention will be described also with respect tofurther features and advantages using exemplary embodiments which willbe described in more detail based on the figures.

Shown are in:

FIG. 1 a section of a double-plate gate valve according to an inventiveexemplary embodiment in a closed position along the central axis whichis parallel to the plate displacement direction;

FIG. 2 a perspective view of a plate box according to an inventiveexemplary embodiment;

FIG. 3 an exploded view of the double-plate gate valve from FIG. 1;

FIG. 4 a perspective exploded view of the upper sealing seat;

FIG. 5 a section of a shut-off plate according to an inventive exemplaryembodiment; and

FIG. 6 a detailed view of the shut-off plates in the closed position ofthe double-plate gate valve from FIG. 1.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The double-plate gate valve according to FIG. 1 is employed in cokingplants, in particular in delayed coker plants, in which coking drums areequipped with shut-off devices. Specifically, the double-plate gatevalve illustrated in FIG. 1 is used for obturating the lower outletopening of a coking drum (bottom de-heading). It is also possible forthe inventive concept to be used in a shut-off device employed foropening and closing the upper outlet opening of the coking drum (topde-heading). Moreover, the inventive concept, respectively the inventionin general, may be used in conjunction with shut-off devices employed inother industrial sectors such as ethylene, FCCU, phosgene, etc. Thedouble-plate gate valve according to the inventive exemplary embodiment,respectively the invention in general, may be used in general as ashut-off device in chemical and petrochemical plants.

FIG. 1 shows a section of a double-plate gate valve 10 in the closedposition. The double-plate gate valve 10 features a housing 11 to whichtwo hoods 12 a and 12 b are flange-mounted. The hoods 12 a, 12 b and thehousing 11 enclose a housing interior within which the elements requiredfor the double-plate gate valve's function are arranged. Shut-off plates20 a and 20 b, between which disc spring packs 25 are arranged, aredisposed between an upper housing sealing seat 13 and a lower housingsealing seat 14. The upper housing sealing seat 13 comprises in itsradial outer area a multiple seal 33 facing the upper shut-off plate 20a which forms part of the sealing surface against which the uppershut-off plate 20 a is pressed. The terms “upper” and “lower” here andhereafter refer to the positional relationships in FIG. 1.

The housing 11 features four gas connections 30. These may be used tointroduce a sealing gas into the housing's 11 interior and to increasethe pressure in the housing's 11 interior. However, other gasconnections not shown in the figure may be provided for this purpose.

The shut-off plates 20 a, 20 b are inserted in a spectacle-shaped platebox 15. The plate box 15 comprises two openings, with one of the twoopenings being loaded with the shut-off plates 20 a, 20 b, and the otheropening being empty. In the example according to FIG. 3, the shut-offplates 20 a, 20 b are disposed in the right-side, respectively generallyrear opening in the closing direction. As an alternative, the shut-offplates 20 a, 20 b may be disposed in the left-side, respectivelygenerally front opening in the closing direction depending onrequirements.

The plate box 15 is displaceable along the direction formed by housing11 and hoods 12 a, 12 b. The double-plate gate valve 10 may thus bemoved between an open and a closed position. In FIG. 1, the double-plategate valve 10 is shown in the closed position. The shut-off plates 20 a,20 b are located in the passage openings between the upper housingsealing seat 13 and the lower housing sealing seat 14 and seal the same.In the open position, the empty box is located within the passageopening so that the same is open.

The plate box 15 is inserted between guiding plates 19 which encapsulateand guide the plate box 15. In this way, the ingress of contaminationsinto the housing interior may be avoided. For displacing the plate box15, and the shut-off plates 20 a and 20 b inserted therein, between theopen and closed positions, the plate box 15, at its right-side outeredge, is connected to an actuating rod 18 extending along thedisplacement direction and protruding out of the hood 12 b. Theactuating rod 18 transfers thrust and traction forces to the plate box15, whereby the double-plate gate valve 10 can be moved between the openand closed positions. For this purpose, the actuating rod 18 may beconnected to a drive that is not shown.

FIG. 2 shows a perspective view of the plate box 15 having two openings.Into the rear opening in the closing direction, the pair of shut-offplates 20 a, 20 b is inserted. The front opening in the closingdirection is empty. The shut-off plates may be exchanged. A dovetailconnection 32, into which a complementary connection element of theactuating rod 18 is inserted, serves the purpose of connecting the platebox 15 and the actuating rod 18. Here, it becomes apparent that theactuating rod does not extend into the area between the shut-off plates20 a and 20 b, but only up to an outer edge of the plate box 15. Theweight of the double-plate gate valve 10 is thus reduced, on the onehand; on the other, a space between the shut-off plates 20 a and 20 b isnot required to be provided for the actuating rod 10 or constructionalelements associated with it.

The upper housing sealing seat 13 is screwed together with the housing11 and can thus be detached from the housing 11. FIG. 3 shows anexploded view of the double-plate gate valve 10 in the same sectionalview as in FIG. 1. The two shut-off plates 20 a, 20 b are exposed toextreme temperatures and need to be serviced at regular intervals. Thedetachable upper housing sealing seat 13 creates a particularlypracticable solution for this.

FIG. 4 shows a perspective view of the double-plate gate valve 10 havingthe upper housing sealing seat 13 detached as for example in the eventof maintenance. The upper housing sealing seat 13 is attached to thehousing 11 to be detachable by means of fastening means 31, in this casescrews. As can be seen from FIG. 4, the hoods 12 a, 12 b are notrequired to be removed from the housing 11 for maintenance so as to getaccess to the shut-off plates 20 a, 20 b, on the contrary, all of theparts in need of maintenance such as gaskets in the sealing seats,shut-off plates 20 a, 20 b or spring elements 25 may be easily madeaccessible through the large opening.

In FIG. 5, a shut-off plate 20 is shown in a sectional view, thestructure of which is identical to both the upper shut-off plate 20 aand the lower shut-off plate 20 b. The shut-off plate 20 is circular andfeatures an outer side 21 and an inner side 22. Referred to as the outerside 21 is in this case always the plate side which, when in theinstalled state, is brought into contact with a housing sealing seat.Accordingly, the shut-off plate's 20 inner sides 22 are facing theopposite shut-off plate in the event of installation.

The outer side 21 of the shut-off plate 20 is smooth, since it needs tobe sealed in the closed position by the housing sealing seat facing it.On the inner side in the plate center a stop area 23 is locatedfeaturing a circular shape that is concentric with the outercircumference of the shut-off plate 20. The stop area 23 constitutes inthis case a stop plate area having a maximum stop thickness DA. Therelation of the shut-off plate diameter RP to the stop area diameter RA,designated as RP:RA, preferably has a value of between 1.5:1 and 3:1.Starting from the stop area 23 the plate tapers radially outward to anedge thickness DR. The relationship of the stop thickness to the edgethickness DA:DR preferably has a value of between 1.5:1 and 2:1.

Uniformly arranged along the circumference, spring element seats 24 aredisposed on the inner side 22 in the edge area of the shut-off plate 20.The spring element seats 24 serve the purpose of receiving the springelements 25 pressing the shut-off plates 20 apart and against therespective sealing seats. Preferentially, at least twelve, furtherpreferentially at least 16 spring elements 25 are provided. Preferably,disc spring packs are used. Other spring types are possible. Forinstance, springs having a gas accumulator and a piston exerting thedesired spring force when the gas storage is heated may be used. Usuallyone and the same spring type is used, e.g. disc spring packs. A parallelcombination of different spring types is also possible, e.g. the discspring packs and the springs having a gas accumulator described above.Particularly preferred, the total force applied by the spring elementsis at least 400 kN, in particular at least 650 kN.

For the installation in a double-plate gate valve 10, a shut-off plate20 just described above is inserted in the plate box 15 with itsexterior side 21 downwards, its spring element seats 24 are providedwith spring elements 25, and a second shut-off plate 20 is placed ontothe provided spring elements 25 with its interior side 22 downwards.

FIG. 6 shows a sectional view of the shut-off plates in this wayinserted into the double-plate gate valve 10 in the closed position.

A gap is formed between the shut-off plates 20 a, 20 b. Due to theshut-off plates' shaping, this gap is narrowest in the region of thestop areas 23 since the shut-off plates 20 a, 20 b here have thegreatest thickness (DA). The width of the gap between the shut-offplates in the stop area 23 is in this case smaller than the thickness ofthe shut-off plates 20 a, 20 b at their outer circumference (DR).Preferably, the gap's width has a value of between 0.5 mm and 10 mm,further preferred of between 1 mm and 8 mm, still further preferred ofbetween 2 mm and 5 mm.

Upon pressure application from outside (indicated by the yellow arrowsfrom above), pressure is exerted upon the upper shut-off plate 20 a. Thespring elements 25 arranged between the shut-off plates 20 a, 20 bwithstand this pressure and press the shut-off plates 20 a, 20 b againsttheir respect housing sealing seats. In the event of one or more springelements 25 failing, the upper shut-off plate 20 a may be deformed dueto the pressure application from outside. In this case, the shut-offplates 20 a, 20 b will make contact in their stop areas 23. The stopareas 23 of the two shut-off plates 20 a, 20 b thus prevent the shut-offplates 20 a, 20 b from excessively deforming upon failure of the springelements 25. Consequently, an excessive deterioration of the tightnesswhich might lead to ingress of contaminations into the housing 11 of thedouble-plate gate valve 10 or a deflection of the shut-off plates 20 a,20 b can be prevented and the safety of the double-plate gate valve 10increased in this way.

The spring elements 25 clamped between the shut-off plates 20 a, 20 bforce the two shut-off plates 20 a, 20 b apart. When the double-plategate valve 10 is moved from the closed to the open position, theshut-off plates 20 a, 20 b are moved along the guiding plates 19 intothe housing interior and the guiding plates 19 absorb the pressure ofthe spring elements 25. In the closed position, the shut-off plates 20a, 20 b are pressed against the upper and lower sealing seats 13 and 14,and the opening is sealed in this manner.

Due to the shut-off plates 20 a, 20 b tapering radially in the radialdirection, a convex deformation of the shut-off plates 20 a, 20 b in theclosed position can be promoted. In this case, the plates will bulgeoutward when sealing gas pressure is applied to the housing 11, wherebythe tightness with respect to the housing sealing seats is furtherincreased. A sealing and scraping edge on the radial inner sides of theupper housing sealing seat 13 may in this case serve as an additionalsealing. The shape of the sealing and scraping edge is adapted to theshut-off plate's 20 a deformation, so that a particularly good sealingeffect is achieved upon applying sealing gas pressure to the housing 11.

In the closed position, the operational safety may be further improvedby applying sealing gas pressure to the housing 11. This offers theadvantage, on the one hand, of being able to prevent the ingress ofcontaminations into the housing's 10 interior through potential leakagesalong the sealing seats. On the other, potential failure of springelements and an associated deterioration of the sealing force can becounteracted as a precaution by an additional sealing gas application.In the event of spring elements failing, the missing sealing force maybe applied by the sealing gas pressure. This serves as an additionalsafety measure and in addition increases the tightness of thedouble-plate gate valve 10.

LIST OF REFERENCE NUMERALS

-   10 double-plate gate valve-   11 housing-   12 a hood-   12 b hood-   13 upper housing sealing seat-   14 lower housing sealing seat-   15 plate box-   18 actuating rod-   19 guiding plates-   20 shut-off plate-   20 a upper shut-off plate-   20 b lower shut-off plate-   21 outer side-   22 inner side-   23 stop area-   24 spring element seat-   25 spring element-   30 gas connection-   31 32 dovetail connection-   33 multiple seal

The invention claimed is:
 1. Double-plate gate valve (10) for fittingsof industrial plants, the double-plate gate valve (10) comprising: ahousing (11) comprising at least one flushing gas connection (30); andtwo shut-off plates (20 a, 20 b) inside the housing (11), the twoshut-off plates being displaceable between an open and a closedposition, wherein: a sealing gas pressure is applied to the inside ofthe housing (11) via the at least one flushing gas connection (30); atleast one of the two shut-off plates (20 a, 20 b) is convexly deformedupon application of the sealing gas pressure; and spring elements (25)such as disc spring packs are arranged between the shut-off plates (20a, 20 b), pressing the shut-off plates (20 a, 20 b) in the closedposition against sealing surfaces arranged on the housing (11) such thatthe entire sealing force required for sealing is provided by the springelements (25).
 2. Double-plate gate valve (10) according to claim 1,wherein the housing comprises an upper housing sealing seat (13) and alower housing sealing seat (14).
 3. Double-plate gate valve (10)according to claim 2, wherein the upper housing sealing seat (13) isconnected to the housing (11) to be detachable so as to enable access tothe shut-off plates (20 a, 20 b).
 4. Double-plate gate valve (10)according to claim 2, wherein the upper housing sealing seat (13)comprises a multiple seal (33) which forms part of the sealing surfaceagainst which the upper shut-off plate (20 a) is pressed in the closedposition.
 5. Double-plate gate valve (10) according to claim 2, whereinat least the upper housing sealing seat (13) comprises a sealing andscraping edge on a radial inner side of the upper housing sealing seat(13); and in the closed position, the radial inner side of the upperhousing sealing seat (13) rests against the upper shut-off plate (20 a).6. Double-plate gate valve (10) according to claim 1, wherein theshut-off plates (20 a, 20 b) are arranged to be movable in aspectacle-shaped plate box (15) displaceable inside the housing. 7.Double-plate gate valve (10) according to claim 1, wherein: a gap isformed between the shut-off plates (20 a, 20 b), a smallest width of thegap is less than the thickness of one of the shut-off plates (20 a, 20b) at an outer circumference.
 8. Double-plate gate valve (10) accordingto claim 5, wherein to an outer edge of the plate box (15), a distal endof an actuating rod (18) is mounted which extends within the housingalong the shut-off plate's (20 a, 20 b) displacement direction away fromthe plate box (15) and by means of which the plate box (15) and theshut-off plates (20 a, 20 b) are displaceable.
 9. Circular shut-offplate (20) for use in the double-plate gate valve (10) according toclaim 1, said plate comprising: a flat outer side (21); a stop area(23), that is concentric to the plate circumference, on the inner side(22), the surface of which runs in parallel to the outer side (21); aplate thickness radially decreasing from the stop area (23) toward theoutside; spring element seats (24) for receiving spring elements (25)arranged along the plate circumference in the edge area on the innerside (22) of the shut-off plate (20).
 10. Double-plate gate valve (10)according to claim 1, wherein the industrial plants are chemical andpetrochemical plants.
 11. Double-plate gate valve (10) according toclaim 1, wherein the spring elements (25) comprise disc spring packs.